1. Field of The Invention
The present invention relates to an interconnect device for use in closed fluid circulating systems, such as cooling systems for high density electronic systems, and in particular to an interconnect device which automatically closes to prevent loss of fluid from the system when mating members of the device are separated.
2. Prior Art
It has been the custom in the electronics industry to rely on natural convection and radiation to cool electronics equipment. Frequently air flow over and about the equipment is supplemented by fans or other means to circulate the air to increase the amount of cooling. Even the forced circulation of air does not always provide adequate cooling and thus attempts have been made to provide closed fluid cooling systems which circulate a cooling fluid through the subject system to provide adequate cooling. Such fluid cooling systems include both liquid cooling and vaporization cooling. Liquid cooling systems cool at a much higher rate than natural radiation and convection cooling and vaporization cooling is approximately twice as efficient as liquid cooling, assuming substantially the same conditions.
A particular area in electronics where the use of fluid cooling systems is being considered is high density applications of integrated circuit type devices. Integrated circuit devices are commonly mounted on relatively thin ceramic plates, commonly referred to as substrates, which have conductors thereon extending from the integrated circuit device or "chip" to the marginal portions of one face of the substrate. Enlarged contact areas or contact pads are formed at the ends of the substrate conductors on one of the faces of the substrate for connecting these substrate conductors to external conductors. The substrate conductors are commonly connected to the external conductors by multi-contact electrical connectors and a variety of types of connectors have been developed for use with previously known designs of ceramic substrates. More recently, and for reasons dictated by substrate manufacturing considerations and other reasons, substrates have been introduced which have their contact pad portions located on their sides rather than on their faces. The numbers of these integrated circuit devices mounted on a single card has been increasing to the extent that lead conduction and case radiation will no longer allow sufficient heat transfer to obtain function temperatures.
The increased cooling efficiency of an internal liquid flow system can be appreciated by comparing the order of magnitude of convective heat transfer coefficients, which are 5-50 BTU/hr. sq. ft. .degree.F for forced air, and 50-2000 BTU/hr. sq. ft. .degree.F for water. The formula for heat transfer by means of water through a system, according to the Federal Engineering Handbook, is P watts = 264 Qw (T.sub.2-T.sub.1)
where
P watts = watts of power absorbed PA1 Qw = flow in gallons per minute PA1 T.sub.1 = the outlet temperature in degrees centigrade PA1 T.sub.2 = the inlet temperature in degree centigrade.
Converting to gallons per hour P watts = 4.4 Qw T.
Assuming a maximum temperature of 20.degree. centigrade, the heat transfer is 85 watts per gallon per hour for water. However, some systems are more likely to use a liquid with a lower freezing point, such as ethyl-glycol, in a liquid cooling system. Ethyl-glycol has a specific heat of 0.571 at 14.9.degree. and approximately 0.6 at 30.degree. C. The same temperature rise of 20.degree. would then conduct approximately 53 watts at a flow rate of 1 gallon per hour. With a maximum junction temperature of 60.degree. C, as recommended by some reliability sources, and a junction to case or heat sink gradiant of 20.degree. C, the cold plate temperatures would be limited to 40.degree. C with ethyl-glycol and inlet temperature could be below freezing. However, an inlet temperature of 0.degree. C is a good starting point and will provide over 100 watts of cooling at 1 gallon an hour of fluid flow.
A typical fluid coolant system for an electronic application would include the following components: a refrigeration and heat exchange; a cooling fluid pump; flexible interconnection conduits; main loop connection devices; distributors; connecting devices between distributors and individual panels or units; connecting devices between panels to boxes and to card cage rails; connecting devices from the back plane to printed circuit cards; and cold plate devices on the cards upon which LS1 devices are mounted. Since this system is a closed fluid system, each point where there is a connecting device must be provided with means which, when the members of the connecting device are separated, prevent the undesirable draining of the cooling fluid from the system. When the fluid system is to be used in conjunction with electronic apparatus, then each of the connections must also provide for electrical interconnection. Composite electrical and fluid connectors of the above described general type are known in the art, for example see U.S. Pat. No. 3,673,541. However, most of these connections, because of size requirements, do not provide adequate means to seal the fluid system whenever the connector is disconnected or opened.